H-section steel is an economical-section and high-efficiency material with a more optimized cross-sectional area distribution and a more reasonable strength-to-weight ratioas all angels of the H-section steel are arranged at right angles. It has been widely used in steel structure buildings. The production methods of H beam mainly include welding and hot- The H-beam production process can be divided into the following procedures: plate pretreatment→cutting and blanking-H-beam assembly→welding→flaw detection→correction→end surface processing→drilling→cleaning and coating.
Requirements for pretreatment of plates
The steel and welding materials used in H steel should have quality certificates. Sampling, inspection and acceptance should be carried out in accordance with requirements and relevant current standards. The inspection records should be made, and mechanical performance experiments should be carried out as required.
Cutting and blanking of steel plates
This process belongs to the leading part before component processing, and its quality has a direct impact on the next process, and even leads to the scrapping of all parts. Therefore, the materials used for H-beams are all qualified plates, and the cutting of steel plates is carried out by CNC cutting machine. Plates with thickness less than 12mm can also be cut by hydraulic pendulum shears. Before cutting, the rust, oil and other debris on the steel plate should be cleaned up. The edge should be cut off about 10-15mm of burrs, and at the same time, the steel plate should be prevented from being bent. The cutting should be made according to the required size specifications and structural characteristics of the components, and the machining allowance and welding shrinkage should be properly considered.
Utilize qualified steel plates. Before assembling, use a polishing machine to derust and polish the welding area, then use an assembly machine for assembly. Before starting the assembling machine, the operator should comprehensively check whether each system of the equipment is normal, and start it after confirming that it is workable. Hoist the lower flange into the assembling machine platform, and then put the web plate into it. The automatic clamping device is operated to make the web plate advance with the centerline of flange plate synchronously. The plates will be spot welded automatically. Finally, turn over the component and hoist the upper flange in place to make the assemble automatically. (As shown below)
H-beam assembly and welding
After passing the quality inspection of the H-beam assembly, it enters the welding process. H-beam assembly welding refers to the weld between the web and the flange plate of H-beam. Generally, fully automatic submerged arc welding will be adopted. The main operating procedures are as follows:
Preparation before welding
Before welding, remove oxide scale, rust, water, paint, and dirt within 50-100mm of the weld area, and it is required to expose the metallic luster. On the surface of the steel to be welded for automatic submerged arc welding, in addition to making the cleaning according to the above requirements, the water, rust, oil and other debris that may be mixed in the flux during the welding process are all cleaned to prevent mixing in the flux. The rust removal of the welding area should generally be carried out before assembly. The components should be protected after they are assembled. If the components are re-corroded or have moisture, oil and other debris, they should be cleaned up again.
The submerged arc welding process is as follows
Filler bottom welding→automatic submerged arc welding→weld seam inspection-clean up the weld seam→repair the unqualified weld seam→submit inspection
Cleaning of the finished weld seam
The weld seam should be cleaned after the beams are finished the welding by welder. After removing the welding slag and welding spatter, the appearance quality of the seam should be checked carefully. The qualified beams need to be submitted for inspection.
The welded H-beam has angular deformation and local bending deformation. Here is the correction method. Firstly use the H-beam flange straightening machine to correct the angular deformation of the flange plate (cold correction), and then make the adjustment by flame heating correction method. No matter which method is used, the principle is not to damage the material.
H-beam end processing
After the welding of the H steel beam is completed, the end face processing should be carried out, the main contents are bevel and lock. Generally the special bevel cutting machine and lock machine will be used.
Use a three-dimensional CNC drilling machine. In the hole making process, when the allowable deviation of the bolt hole exceeds the deviation value, the steel plate shall not be used for filling, and the welding rod which matching the material of the base material shall be used for repairing and re-making the hole.
H-beam coating construction
Before painting, check whether the steel structure is qualified. Remove rust, weld spatter, oil, dust, and etc. before painting. In order to ensure the quality of painting, rust removal should be carried out. After the base layer is prepared, blend the anti-rust paint, control the viscosity, consistency, and thinness of the paint, and stir it thoroughly when mixing. When spraying the first coat of primer, the brushing direction should be consistent, and the rubbing should be neat. After the first layer is dry, spray the second layer. The spraying direction of the second layer is perpendicular to the direction of the first layer so that the thickness of the paint film will be uniform.
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